A progressing cavity pump generally comprises a cylindrical armature, a stator arranged in the armature and having a helical inner shape, and a helical rotor arranged in said stator. Cavities, also known as cells, are delimited between the rotor and the stator. In operation, the rotor is made to rotate. The rotation of the rotor leads to the displacement or pumping of a fluid from one cavity to the cavity adjacent thereto, from one end of the pump, known as intake, to the opposite end, known as discharge.
During the pumping of a multi-phase fluid comprising a gaseous phase, a volume of gas taken in at the pump inlet is compressed progressively from intake to discharge. This compression leads to a significant increase in the temperature inside the pump, which damages the mechanical strength of the rotor and stator, for example by scorching of the elastomer forming the stator, and reduces the service life of a progressing cavity pump.
To overcome this drawback, patent application EP 1 559 913 proposes a progressing cavity pump comprising a rotor provided with channels connecting two or more cavities. During pumping, the pumped fluid circulates from one cavity to the next via these channels, thus ensuring that the pressure is balanced between the cavities connected to each other and thus reducing the temperature increase inside the stator.